This invention relates to endless track assemblies for smowmobiles and, more particularly, to apparatus for mounting bogie wheels for spacing the endless track from the frame members or slide rails of such an assembly.
Generally, snowmobiles and other similar multiterrain vehicles utilize endless track assemblies for obtaining movement over snow or other supporting surfaces. The flexible endless tracks are supported on framewoks having idler wheels at either end thereof around which the track is driven in a closed path. Two types of supporting systems are typically used to support the track between the sets of idler wheels. In the pure rail system, parallel slide rails slidingly engage the inside surface of the endless track and force it against the supporting surface. In the pure bogie system, a plurality of small wheels or bogie wheels space the track away from the intermediate supporting framework of the assembly. Combinations of these two systems have also been used wherein bogie wheels are supported on continuous axles extending between the two parallel rail members or wherein a series of single bogie wheels extends from the laterally outward sides of the rails along their length. Each of these various supporting systems has its own advantages and disadvantages.
Although the pure rail systems provide greater lateral stability for the snowmobile since such systems are generally utilized with tracks including devices which keep the track in alignment with the slidably engaged rail, the pure bogie systems generally require a smaller amount of horsepower to produce the same speed as in a corresponding sled using the pure rail system since the bogie wheels minimize the frictional contact between the endless track and its supporting framework. Several attempts have been made to use the best of both of these systems in combination bogie-rail systems. However, prior known combination systems have rigidified the track assembly, thereby reducing its all-terrain efficiency. More importantly, the bogie wheel arrangements in certain of the prior known combination systems have allowed the sliding surfaces of the slide rails to deteriorate and wear unevenly. Such wear impairs both the handling and performance characteristics of the sled therefore necessitating more frequent maintenance and repair.
Additionally, the preveiously known track supporting systems have necessitated a constant amount of track in contact with the supporting snow surface. It has been founr dhat a greater amount of track in contact with the supporting surface produces better handling in conditions of ice, high speeds along straight paths and in deep, heavy snow because of the greater frictional contact, greater stability, and greater surface area produced thereby. Conversely, a lesser amount of track in contact with the supporting surface enables quicker starts, the handling of more varied terrin, and a greater speed from a given size engine because of the reduced drag or friction on the track. Conversion between these two types of track configurations has heretofore been extremely difficult and time-consuming because of the extensive modification required to modify the prior known track assemblies such as those described above.